The Solar System

PERSPECTIVE: ORIGINS 187

Review Questions

1. What evidence could you cite that there is an interstellar medium?


2. Why are protostars diffi cult to observe at visible wavelengths?


3. How are protostars related to planet formation?


4. How do stars like the sun die?


5. How do massive stars die?


6. What is the difference between the Milky Way and the Milky Way
   Galaxy?


7. Describe how star formation is related to gas and dust in galaxies such
   as ellipticals and spirals.
   8. What evidence can you site to show that the universe is expanding?
   That there really was a big bang?
   9. Why would it be accurate to say that the big bang formed the matter
   in your body, but the stars formed the atoms?
   10. How Do We Know? How can scientists use mathematical models to
   understand processed that they cannot observe directly?
   11. How Do We Know? Why do scientists hesitate to say they “believe”
   in a certain theory?
   12. How Do We Know? How would you respond to someone who said,
   “Oh, that’s only a theory”?